onmode -F: Free unused memory segments

When you execute onmode -F, the memory manager examines each memory pool for unused memory. When the memory manager locates blocks of unused memory, it immediately frees the memory. After the memory manager checks each memory pool, it begins checking memory segments and frees any that the database server no longer needs.

It is recommended that you run onmode -F from an operating-system scheduling facility regularly and after the database server performs any function that creates additional memory segments, including large index builds, sorts, or backups.

Running onmode -F causes a significant degradation of performance for any users that are active when you execute the utility. Although the execution time is brief (1 to 2 seconds), degradation for a single-user database server can reach 100 percent. Systems with multiple CPU virtual processors experience proportionately less degradation.

To confirm that onmode freed unused memory, check your message log. If the memory manager frees one or more segments, it displays a message that indicates how many segments and bytes of memory were freed.

This command has an equivalent SQL administration API function.